Original Research

Preliminary Observations of Veterans Without HIV Who Have Mycobacterium avium Complex Pulmonary Disease

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Background: Nontuberculous Mycobacterium -related pulmonary disease (NTM-PD) is commonly caused by Mycobacterium avium complex (MAC) and is increasingly recognized in veterans. NTM-PD carries an increased risk of mortality, and lack of treatment is an predictor of increased mortality.

Methods: We describe the clinical characteristics of veterans diagnosed with MAC-pulmonary disease (MAC-PD) followed in a health care setting with varying treatment practices. We reviewed the electronic health records of veterans without HIV who had sputum culture-positive MAC-PD followed at the Jesse Brown Veteran Affairs Medical Center in Chicago, Illinois.

Results: We identified 19 veterans diagnosed with MAC-PD between 2008 and 2019. They were predominantly male (89.5%), Black (73.6%), and had a median age of 74 years. Sixteen veterans (84.2%) had underlying lung disease, and 16 (84.2%) were current or former smokers. Respiratory symptoms were reported in 17 veterans (89.5%). Guideline-directed combination antimycobacterial therapy was initiated in 10 veterans (52.6%); however, only 5 (50.0%) completed treatment. Comorbidities, symptoms, and findings on chest imaging at diagnosis were similar among treated and untreated veterans.

Conclusions: Clinical, imaging, and treatment attributes of MAC-PD in veterans without HIV who reside in metropolitan Chicago are heterogeneous and are associated with a relatively high mortality rate. Further studies are warranted to characterize MAC-PD and its treatment in veterans without HIV who reside in underresourced urban communities in the US.


 

References

Nontuberculous Mycobacterium (NTM) is a ubiquitous organism known to cause a variety of infections in susceptible hosts; however, pulmonary infection is the most common. Mycobacterium avium complex (MAC) is the most prevalent cause of NTM-related pulmonary disease (NTM-PD) and is associated with underlying structural lung disease, such as chronic obstructive pulmonary disease (COPD) and noncystic fibrosis bronchiectasis.1-3

Diagnosis of NTM-PD requires (1) symptoms or radiographic abnormality; and (2) at least 2 sputum cultures positive with the same organism or at least 1 positive culture result on bronchoscopy (wash, lavage, or biopsy).1 Notably, the natural history of untreated NTM-PD varies, though even mild disease may progress substantially.4-6 Progressive disease is more likely to occur in those with a positive smear or more extensive radiographic findings at the initial diagnosis.7 A nationwide Medicare-based study showed that patients with NTM-PD had a higher rate of all-cause mortality than did patients without NTM-PD.8 In a study of 123 patients from Taiwan with MAC-PD, lack of treatment was an independent predictor of mortality.9 Given the risk of progressive morbidity and mortality, recent guidelines recommend initiation of a susceptibility driven, macrolide-based, 3-drug treatment regimen over watchful waiting.10

MAC-PD is increasingly recognized among US veterans.11,12 The Jesse Brown Veterans Affairs Medical Center (JBVAMC) in south/west Chicago serves a large, predominantly Black male population of veterans many of whom are socioeconomically underresourced, and half are aged ≥ 65 years. We observed that initiation of guideline-directed therapy in veterans with MAC-PD at JBVAMC varied among health care professionals (HCPs) in the pulmonary clinic. Therefore, the purpose of this retrospective study was to describe and compare the characteristics of veterans without HIV were diagnosed with MAC-PD and managed at JBVAMC.

Methods

The hospital microbiology department identified veterans diagnosed with NTM at JBVAMC between October 2008 and July 2019. Veterans included in the study were considered to have MAC-PD per American Thoracic Society (ATS)/Infectious Diseases Society of America (ISDA) guidelines and those diagnosed with HIV were excluded from analysis. The electronic health record (EHR) was queried for pertinent demographics, smoking history, comorbidities, and symptoms at the time of a positive mycobacterial culture. Computed tomography (CT) and pulmonary function tests (PFTs) performed within 1 year of diagnosis were included. PFTs were assessed in accordance with Global Initiative for Obstructive Lung Disease (GOLD) criteria, with normal forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) values defined as ≥ 80% and a normal FEV1/FVC ratio defined as ≥ 70. The diffusion capacity of lung for carbon monoxide (DLCO) was assessed per 2017 European Respiratory Society (ERS) technical standards and was considered reduced if below the lower limit of normal.13 Information regarding treatment decisions, initiation, and cessation were collected. All-cause mortality was recorded if available in the EHR at the time of data collection.

Statistical analysis was performed using Mann-Whitney U and Fisher exact tests where appropriate. P < .05 was considered statistically significant. The study was approved by the JBVAMC Institutional Review Board.

Results

We identified 43 veterans who had a positive culture for MAC; however, only 19 veterans met the diagnostic criteria for MAC-PD and were included in the study (Table). The cohort included predominantly Black and male veterans with a median age of 74 years at time of diagnosis (range, 45-92). Sixteen veterans had underlying lung disease (84.2%), and 16 (84.2%) were current or former smokers. Common comorbidities included COPD, obstructive sleep apnea, gastroesophageal reflux disease, and lung cancer. Respiratory symptoms were reported in 17 veterans (89.5%), 15 (78.9%) had a chronic cough, and 10 (52.6%) had dyspnea. Fifteen veterans had a chest CT scan within 1 year of diagnosis: A nodular and tree-in-bud pattern was most commonly found in 13 (86.7%) of veterans. Thirteen veterans had PFTs within 1 year of MAC-PD diagnosis, of whom 6 had a restrictive pattern with percent predicted FVC < 80%, and 9 had evidence of obstruction with FEV1/FVC < 70. DLCO was below the lower limit of normal in 18 veterans. Finally, 6 veterans were deceased at the time of the study.

Patient Demographics

Of the 19 veterans, guideline-directed, combination antimycobacterial therapy for MAC-PD was initiated in only 10 (52.6%) patients due to presence of symptoms and/or imaging abnormalities. Treatment was deferred due to improved symptoms, concern for adverse events (AEs), or lost to follow-up. Five veterans stopped treatment prematurely due to AEs, lost to follow-up, or all-cause mortality. Assessment of differences between treated and untreated groups revealed no significant difference in race, sex, age, body mass index (BMI), symptom presence, or chest CT abnormalities. There was no statistically significant difference in all-cause mortality (40% and 22.2% in treated and untreated group, respectively).

To further understand the differences of this cohort, the 13 veterans alive at time of the study were compared with the 6 who had since died of all-cause mortality. No statistically significant differences were found.

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